The presence of tanks under pressure close to people or sensitive goods, or in a confined space, gives rise to problems of safety. The usual solution consists in using a container that is strong, and thus heavy. In addition, the optimum shape for such a container enabling it to withstand internal pressure well often limits the ways in which it can be installed, in particular on a motor vehicle. This takes up a large amount of the available volume in the vehicle. In addition, safety standards mean that vehicles fitted with such tanks can be banned from having access to road tunnels.